Antifriction pipe protector



Dec. 3, 1.929, G. E. FENTREss ANTIFRICTION PIPE PROTECTOR Filed July 6, 1927 Patented Dec. 3, 1929 VUNiTaD STATES PATENT OFFICE GEORGE E. FENTRESS, OF LOS ANGELES, CALIFORNIA, ASSIGNOR OF ONE-HALF T HARRY H. ISAACS, OF LOS ANGELES, CALIFORNIA ANTIFRICTION PIPE PROTECTOR Application filed. July 6i, 1927. Serial No. 203,791.

My invention relates to the art of drilling 'oil wells, being more particularly a sleeve attachable to the ordinary drill pipe, commonly used in the rotary drilling of oil wells, which sleeve has mounted thereon a collar freely rotatable on the sleeve on balls or other antifriction devices.

In the drilling of oil wells it commonly occurs that depths of several thousand feet. are encountered, a. casing being used for retaining the sides of the wells which also affords protection for the string of tools which is operated through the casing.

It is common practice to shut off water from entering the well by the usual methods ofcernenting, that is, charges of cement are forced through the bottom of the casing and up around the casing into the formation, which necessitates that the casing at all times remain tight and free from leaks. In drilling, however, the drill pipe frequently bends and rubs against the casing and, due to the rotation of the drill pipe, results in wearing holes in the casing, weakening the casing and permitting water to enter it and destroy the effectiveness of the cementing operation.

In my application tiled December 18, 1926, Serial No. 155,675, I described and claimed an anti-friction device which can be placed on the drill pipe at any preferred point in its length without 'changing the ordinary equipment of drill pipe, collars or tool joints. My present invention is a device of similar character but is directed to an improved construction by which the costs of making and placing it in position are reduced and the effectiveness of the device increased.

Other objects' and advantages will appear hereinafter from the following description.

Referring to the drawings, which are for illustrative purposes only,

Figure 1 is an elevation of my improved protector, mounted on a section of drill pipe, parts being broken away.

Figure 2 is a cross-section on the line 2-2 of Figure 1, and

Figure 3 is a cross-section on the line 3 3 of Figure 1.

Referring to the three figures, 11 is a sec- 50 tion of the drill pipe over which is slipped the inner sleeve 12, which is preferably made from seamless steel tubing of low carbon content. This sleeve should be machined outside lto exact standard size the hole being left about 1/8 undersize, and then carbonized to a penetration of say -lt-f. The hole is then bored out to a standard inside diameter' and the sleeve heat treated, bringing the outer surface on which the balls revolve to a hardness of 85/90 scleroscope while the body of the sleeve remains relatively soft. The stan dard inside diameter of this sleeve should be not less than the largest outside diameter of the nominal size drill pipe on which it is to be used, such drill pipes varying by as much as /S in diameter in any one nominal size. The sleeve should be a loose iit or a slip fit on the pipe and should never be forced on, as, if distorted from a true circle by forcing, the ball race will not be true and will rapidly hammer out. The sleeve 12 is not fastened to the drill pipe.

The bearing sleeve 13 is preferably a ring forging of 40 to 50 carbon steel, machined to size and the ball grooves formed, heat treated and drawn to a hardness of scleroscope. This sleeve thus has a uniform hardness inside and outside and will withstand the wear resulting from contact with the casing. The bearing sleeve, as shown in Figure 1, is of substantially less length than the sleeve 12.

The balls 14e are high-duty f chrome or chrome-molybdenum steel balls of the best quality.

The. split rings 15 are preferably made from soft steel ring forgings and are not hardened. The inside shoulder 16 should lit snugly over the sleeve 12. The tapered end 17 may desirably have a taper of about 1 per foot and is longitudinally split or kerfed at' a plurality of points on yits circumference, as at 18. The inside diameter 19 of these rings should be about g1g larger than the nominal outside diameter of the drill pipe. After being completely machined these rings may be split longitudinally into halves` as at 20. The width of this opening is exaggerated in the drawing-it should be no more than a thick saw-kerf or the kerf of an Oxy-acetyiene cutting tool. The purpose of splitting vthe ring is to facilitate fitting it around the pipe, and is optional.

The compression rings 21 are also made from soft steel ring forgings and need not be hardened. The inside taper 21sl1ould fit the taper 17 of the split ring, and both tapers should be true and smooth. At the opposite end of the compression-ring is formed a recess 23, which'should be a slip lit on the shoulder 24 formed in the split ring 15.

In assembling this fitting the following steps are taken. The bearing sleeve 13 is upended and the inner sleeve 12 inserted in its lower end, up to the level of the iirst ball race. This ring of balls is'inserted, the inner sleeve moved up to the second race and so on until all the balls are in place and the two sleeves in the position shown, after which the assembly may be slipped over the pipe into its preferred position.

The two split rings 15 are then placed around the ends of the sleeve 12 and retained in position by slipping the compression rings 21 over them. Vhen the rings 15 are brought .up solidly against the ends of the sleeves 12, the clearance v25 between ring 15 and bearing sleeve 13 should 'be no more than 2 or 3/100() of an inch, to exclude solids from the ball chamber. This clearance is adjusted in advance, preferably on the length of the innen sleeve 12.

A suitable split screw clamp, not shown, is now passed over the ends of the compression rings 29 and these rings are drawn toward each other, sliding up the taper 17 on the split rings 15, which are restrained from endmovement by abutment against the end of sleeve 12, as at 26. This relative movement up the taper collapses the lrerfed ends .of the split ring and clamps them firmly `against and around the drill pipe. Finally, the compression rings are held in permanent 4position by welding or brazing them to the split rings as indicated at 27.

VThe division of the Vsplit ring into halves may leave an opening as at 2O through which sand or other abrasive material might enter the ball chamber and cause undue wear. This opening may be closed by drilling a hole as at 28, of a diameter materially greater than the Width ofthe opening 20 as assembled, and plugging this hole with a Hush screw or with welding steel or brass. This plug should reach to the surface of the inner ring 12 and will prevent any solid matter from passing through the slot 2O into the ball chamber.

This type of construction has material advantages over the types previously disclosed in which the inner'sleeve on .which the balls ride is in one piece with the split ends. `By the construction here shown a very hardand durable inner ring may be used in combination with soft yand easily clamped taper kerfed ends, no welding is done on hardened pieces,

and the single weld is applied to two soft steel rings and not at any point to the pipe. If a screw plug be used to close the slot the bearing ring is not heated at any point after hardening. These improvements add greatly to the durability of the fitting and also reduce the manufacturing and assembling cost. This fitting canalso be assembled for shipment as a Complete .unit ready t0 be rulin place and clamped onl the pipe.

Vhile I have shown a preferred construction ofmy `improved pipe protector in great detail, I Vdo not wish to be limited to the exact constructign shown, but solely by the attached claims.

I claim as my invention:

1. An anti-friction protector for attaching to drill pipe, comprising: a cylindrical inner sleeve fitting loosely on the pipe, a bearing sleeve circumferentially surrounding said inner sleeve and spaced therefrom bya plurality of circumferential rows of bearing balls, outside-tapered rings adapted to be placed abutting each end of saidinner sleeve and closely approaching the ends of said bearing sleeve, said rings being nonintegral with said sleeve and being longitudinally kerfed through their ta ered ends, and inside- .tapered rings littecllover said kerfedends and adapted to compress said ,ends against rthe pipe when said inside-tapered rings are drawntoward each other. i

2. An antiffriction protector for .drill pipe, comprising: a hardened steel cylindrical inner sleeve fitting loosely on the pipe, a hardened steel bearing sleeve circumferentially surrounding said inner sleeve and spaced .therefrom by a plurality of circumferential rows of bearing balls, independent rings abutting each end of said inner sleeve and ,closely approaching each end of said bearing slee-ve, the outer ends of said rings being of soft steel, outwardly ,tapered and longitudinally kerfed through said tapered ends, and inside tapered rings fitting over said tapered lrerfed ends and adapted to compress vsaid ends against the pipe when said inside taperedrings are prawn toward each other.

`3. An anti-friction protector for drill pipe, `comprising in combination: the cylindrical inner sleeve 12, the bearing sleeve 18, the bearing balls 14, the independent tapered rings 15 ,and the compression rings 21, Vsubstantially as described.

In witness that I claim theiforegoing I have hereunto subscribed my'naine this 270th. day of June, 1927. l

`GEORGE E. FENTRESS. 

